Notre Dame, Fr., Our Lady.
O Tempora! O Mores! L., Oh the times! Oh the manners!
Passé, Fr., out of date.
Penchant, Fr., a strong or particular liking.
Pièce de résistance, Fr., something substantial by way of entertainment; most substantial course of a dinner; literally, a piece of resistance (a main event or incident).
Pour prendre congé, Fr., to depart, take leave. (P.p.c. on calling cards meaning the departure of a caller for a long voyage, hence a parting call.)
Prima donna, Ital., the chief woman vocalist of a concert.
Pro patria, L., for our country.
Protégée, Fr., under the protection of another.
Rendezvous, Fr., an appointed place for a meeting.